This invention relates to shaking mechanisms for bag-like filters and, in one aspect, relates to shaking mechanisms for periodically dislodging particulate material collected on a surface of bag-like filters used in abrasive blasting cabinets and the like.
Abrasive blast cabinets typically include a blast compartment in which the article or articles to be cleaned or polished by an abrasive blasting material is placed. The operator usually reaches through arm holes protected by rubber gloves and, observing through a front window in the compartment, either picks up an article to be cleaned and moves it under a stationary blast nozzle or picks up a portable blast nozzle and moves it about to direct a jet stream of the abrasive material over the article. Smaller, dust-forming particles of the abrasive material tend to disperse throughout the blast compartment during the cleaning operation and, if not removed, can partially or completely mask visibility of the article being cleaned or polished to the operator.
One approach for removing these dust-forming particles is to purge the blast compartment by directing a flow of air therethrough and circulating the dust-ladened air exiting from the blast compartment through the interior of one or more bag-like filters to remove the particulate material. In order to prevent plugging, the filter bags must be periodically shocked or shaken to dislodge and remove the particulate material collecting on the inner surface.
Examples of prior shaking mechanisms are disclosed in U.S. Pat. Nos. 1,601,148, 1,743,934 and 1,835,093. These mechanisms provide primarily only a lateral movement of the filter bags. The mechanism disclosed in U.S. Pat. No. 1,743,934 includes U-shaped shaker members which engage the outer surfaces of the filter bags and, therefore, can cause considerable wear. The manually operated shaking mechanism disclosed in U.S. Pat. No. 1,835,093 includes a hand lever which is located at a side or rear of the device and protrudes from the exterior of the device. Thus, in addition to increasing the overall outside dimension, some space from the wall and/or adjacent equipment must be made available to provide the operator with access to the hand lever.